Knife sharpener



F. R. CHESTER KNIFE SHARPENER Oct.` 9, 1945.

Filed Sept. 4, 1944 Patented Oct. 9, 1945 i l KNIFE SHARBENER f kFnlmk a. ohsteamanhartan Beech, Calif.,A i Appii'eation september 4, 1944, serial No. 552,605 c Claims. (ci. ref-,85) f .'My invention relates to knife Sharpeners which are adapted particularly to householdy use.V In every1 household 4`knives are used' for carving meats and otherwise cutting foodand other material.l The ,cutting edges of such knives become dulled byuse, and'it is a specific purpose of my invention to provide a knife Sharpener for restoring such edges. My invention can be used for other purposes, this use is described merely as illustrative of one way in which it can be used, and further objects and advantages will be obvious to one skilled in the art.

Referring to the drawing, which is for illustrative purposes only,

Fig. 1 is a View of a preferred embodiment of my invention asseen from above.

Fig. 2 is an elevation of this embodiment, the case which forms a supporting structure being shown in section.

Fig. 3 is a section on a plane represented by the line 3-3 of Fig. 2 as viewed in the direction of the arrows adjacent the line 3--3.

Fig. 4 is a side elevation of said embodiment.

Fig. 5 is a section through the helix.

The case or supporting structure II is preferably formed of sheet metal and is provided with feet or lugs I2 and I2a having holes I3 therein. Screws (not shown) may be used in the holes I3 to secure the case II to a shelf or board (not shown), Secured inside the case Il at the lefthand side thereof, as seen in Fig. 2, is a stud I4 which is bored to receive a shaft I5, the other end of which is secured in the right-hand side of the case II. Mounted rotatably and movable axially on the stud I4 is a cap I6, and mounted rotatably and movable axially on the shaft I5 is a cap I1. Secured in and between the caps I6 and I1 is a helix I8. This helix is preferably formed of a material that is somewhat harder than the knives to be sharpened and may be made of a trapezoidal strip as shown in Fig. 5. 'I'he outer corners I9 of this strip form sharp cutting edges.

Knives, however, may be sharpened by filing or rolling, and the helix may be of different cross section, for example, circular; the ille teeth or corrugations may be placed on the sharpening surfaces; or, indeed, the knife edge may be improved by rolling between smooth surfaces on the helix.

Mounted about the shaft l5 is a compression spring 20, one end of which presses against-the cap I'I, and the other end of which presses against the end of the stud I4. This spring tends to hold the helix assembly consisting of the helix I8 and the caps I6 and Il, which are secured thereto, in its extreme right-hand position as shown in Fig. 2or `to return it to this position if theasser'nbly'is freetoso move.

`lli/'here a relatively light helix is used, I may `supply .rollers 3 I and 32, `each oflwhich turnsA on a shaft 33 secured at either end in the case.

The helix I8 rolls and slides on the rollers 3l and 32. Other means of support, may be used, for example, constraining the helix to move inside a cylindrical wall of the case I I.

Formed in the top of the case Il is a groove 2i in which a knife 22, shown in dotted lines in Fig. 3, may be placed, the sides of this groove forming guides which hold the center of the knife blade in a plane to which the axis of the helix is perpendicular. The knife 22 may, however, be moved to the right or left as viewed in Fig. 3, in thedirections of the arrows 23.

The method of operationis as follows: The case I I being secured by screws to a shelf, table,

or other support, the knife 22 is inserted in the slot 2| and is held down in contact with the cutting edges i9, and the knife is pulled back and forth in the directions of the arrows 23. This rotates the helix assembly so that the cutting edges I9 are moved over the sides `of the knife, producing a sharp cutting edge having the angle P as shown in Fig. 2.

The device may be ma-de quite small; in fact, for sharpening household knives the helix need not be over an inch in outside diameter. In a helix which has ve complete turns and a diameter of one inch, each of the cutting edges I9 has a total effective length of about sixteen inches.

This device is sold under the name of Rotary steel knife Sharpener.

I claim as my invention: v

1. A knife Sharpener, comprising: a helix formed of material Vthat is preferably harder than the material of the knives to be sharpened; and means for so guiding the knife that it can be moved through the helix in such a manner as to cause the sides of the knife to contact sharpening surfaces of adjacent turns of the helix.

2. A knife Sharpener, comprising: a helix formed of material that is preferably harder than the material of the knives to be sharpened; means for so mounting the helix that it can rotate as the knife is pushed therethrough;` and means for so guiding the knife that it can be moved through the helix in such a manner asto cause the sides of the knife to contact sharpening surfaces of adjacent turns of the helix.

3. A knife Sharpener, comprising: a helix formed of material which is preferably harder than the material of the knives to be sharpened, said helix being made of material having a cross section such that a cutting edge is formed on the outer corners of the turns of the helix; and a supporting structure for the helix, having guiding surfaces for a knife so placed as to cause the sides of the knife to be acted upon by said edge as the knife is moved through the helix.

4. A knife Sharpener, comprising: a helix formed of material which is V,preferably harder than the :material rof Lithe-knives to @be ssharpened, said helix being made o'f material having a cross section such that a cutting edge is formed on -the outer corners of the turns of the helix; a supporting structure for the helix, having guiding surfaces for a knife so placed as to cause the sides of the knife to be acted uponby-sai-dedge lasfthe knife is moved through thedielix; .andrmeansfor so mounting said helix in said supporting structure that the helix can turn about the axis'pfthe helix as Vthe ,knife smoved through .the helix.

`5. A ,knife Sharpener, nomprising: a Ahelix formed of .material AWhich iis preferably harder .thanthematerial of the 'fkxiii/ es to b e sharpened, said-he`lix ".heingmarle .o'f.material having across sectionsuchthat .,a ,cutting edge fis formed ongthe outer corners of the turns of the helix; a supporting structure for the helix, having guiding surfaces for a knife so placed as to cause the sides of the knife to be acted upon by said edge as the knife is moved through Athe helix; and a shaft supported in said supporting structure, the helix being supported on said shaft so that it is free to turn and move axially thereon.

6. A knife Sharpener, comprising: a helix formed of material which ,ispreferably harder than the material of thekriives to fbessharpened, saidhelix being made o'f material 'having a cross `section such that a cutting edge is formed on the outer corners of the turns of the helix; a sup- ;puntrigstructure for the helix, having guiding surfaces for a knife so placed as to cause the fsideso'fthe knife to be acted upon by said edge 4.as A.the .knifeismoved through the helix; a shaft supported in said supporting structure, the helix being supported on said shaft so that it is free to turn ,and move axially thereon; :and .aspring .so placed as to resist axial movement of said Ihelix on said Ashaft and toreturnlsadhe'lixlto its initial axial position ori-.said shaft when saidkni'fe is ltakenout 0T Contact with salidhlix.

TR. CHESTER. 

